A tactile sensor described in patent document GB-A 2,136,966 has a first plate which is situated on conducting strips extending in an X direction, the conducting strips being attached at one end to resistance strips extending at right angles thereto. Spaced therefrom is a centre plate made of a conductive material. At a distance from this plate, a second plate is provided which is constructed similarly as the first plate but is rotated by 90.degree. relative to it, so that the conducting strips extend in a Y direction. A reference potential is applied to the centre plate which is also applied to one end of each of the two resistance strips. At the other end of each of the resistance strips, the potential is sensed. If a pressure is exerted on the sensor which causes the centre plate to come into contact with the conducting strips of the first and second plates, then the location at which the pressure acts on the sensor can be determined by sensing the potentials at the other ends of the resistance strips.
Thus, that tactile sensor has numerous pressure-sensitive measuring cells each comprised of a first conductor path associated with the first plate, a second conductor path associated with the second plate and the conductive material of the centre plate.
Although it is possible with that tactile sensor to detect the location where the pressure acts, it is however not possible to determine the amount of pressure.
In order to be able to ascertain the amount of a pressure and the location where the pressure acts, plates can be used which are made from a material whose electrical resistance varies with the amount of pressure. A tactile sensor of this type is, for example, the subject of U.S. Pat. No. 4,208,648. The latter sensor is comprised of a first plate in which electrical conductors extend in an X direction, a centre plate made of the above-mentioned material and a second plate in which the conductors extend in a Y direction. The disadvantage of this tactile sensor is that the location and amount of pressure can only be measured relatively inaccurately. Moreover, the pressure-resistance ratio of the centre plate depends on many factors, such as, for example, the ambient temperature.